1. Field of the Invention
The present invention relates to a numerical controller, and particularly relates to a numerical controller having a function of optimizing a corner path at a corner of tangent continuity.
2. Description of the Related Art
When a block that issues a processing command is continuously executed in numerical control for controlling a machine tool, and a direction of movement changes at a joint of blocks (hereinafter referred to as a block junction), a shock may be generated in the tool. To control such a shock, a conventional art disclosed in JP 2014-21759 A attempts to smoothly connect adjacent blocks by inserting a curve, a distance of which from a command path falls within a preset tolerance (allowable error amount), into a block junction of a processing program as illustrated in FIG. 6.
When the conventional art disclosed in JP 2014-21759 A is used, there is an effect that a cycle time of processing may be shortened since an inward turning amount of the corner path changes according to a magnitude of the tolerance in addition to controlling the shock at the block junction as described above.
Shortening of the cycle time by inserting the curve into the block junction described above may obtain a great effect when a tangential direction of the corner path is discontinuous (when a direction of movement of the tool abruptly changes before and after the block junction) as illustrated at a top of FIG. 7. However, when the tangential direction of the corner path is continuous (when the tangential direction smoothly changes in the whole corner path) as illustrated at a bottom of FIG. 7, the inward turning amount is restricted even when the curve is inserted into the block junction after increasing the tolerance, and thus a great effect may not be obtained.